SADIA KHAN, lead for self-care, practice division, Royal Pharmaceutical Society, replies:

We have discussed this with the BNF and the correspondents are correct. The BNF advises that following instillation of eye drops in general, the eye should be kept closed for as long as possible. In practice however, a number of other points need to be considered, eg, the nature of the condition, the patient’s convenience and comfort and the viscosity of the drops. These might all have a bearing on how the eye drops are best applied. Patient information leaflets for some eye drops advocate blinking a few times following eye drop instillation. The manufacturers of over-the-counter chloramphenicol (Optrex/Galpharm) have confirmed that they support the advice provided in the Society’s guidance. With an ocular infection, it is important that the antibiotic comes into contact with all parts of the eye: blinking helps to spread the drug.

I would be interested to hear of any evidence to suggest that chloramphenicol’s clinical efficacy is improved by keeping the eye closed for a minute or two.